Welcome to the joys of pcs
Just FYI, Im using a crt, and I havent had any blackouts since my upgrade
Im guessing because, 1 - the A64 uses less power than my previous Varton, and 2 - this 7800 may use less power than my previous 5900XT (not 100% sure on this). Also my blackouts only happend when my pc was idle also, hense taking a guess that our problems maybe the same. Im taking a guess that my problem was due to the PSU, never looked into it though as I dont have any quality PSUs just laying around but I am defently upgrading my PSU when I go SLi as I dont want to take any chances. Are both PSUs you have tried no name? Do you know anyone that has a good quality PSU that you can try? I wouldnt want you to go and buy a new PSU only to find out that it wasnt the problem. The reason that Im thinking that it isnt your card, is that I havent read many people having this problem, and with the amount of nvidia cards sold, you would think that if it was that card, you would see more people posting about it.

Trouble shooting pcs can be a pain at times, one time I thought I killed my Barton 2500+, left it out of my pc for a couple of months, put it back in and it worked! Sometimes it can be as simple as a bios setting, like wake-up on LAN being enabled etc. Have you tried the card itself in a different pc yet? I would do that before sending it back.

Also, just noticed that you are overclocking, try running everything at stock just to see if it helps, as usually when OC'ng the cpu we raise the voltage, but not so when OC'ng the videocard, unless you flash the cards bios.

yea I just set my bios back to default so its not overclocked now..the problem is I can just test parts of my sisters computer since I gave it to her a while back but where im from my friends etc.. dont have computers they just hang out in the streets rather then be on the PC so its always hard for me to test other things as in gettin a mainboard, ram, cpus , graphicards and so on Im using PCs since 5yrs and whenever i had a problem the only way find out what was causing the problem was to save money n buy a new mainboard lets say..oh have a small doubt in me about the grahpic card jsut because of what u said above i had a similar thought but I just cant explain it to myself that ever since 3weeks ago I had money to get a new graphiccard that my computer messes up I just have to blame the graphiccard lol..but I run the cpu now at 166FSb (1500mhz) and the RAM at 200mhz eventho its better to run both same speed but just to make sure everything is at default settings..the problem is this that I just can see it that nothing happens e.g. no blackouts and jsut when its time when the shop closes (where i want to return the card) the blackout comes..it was like that today aswell..i thought ok it runs fine like that but then it was 8pm the shops closed and 1 hour later i get a blackout lol..so I just wanna give it back tomorrow but I was readin of a similar problem somewhere a guy had with a 6600GT n he returned it n same thing happend again..then he bought a new PSU..same thing happend again n then he bought an ATI n same thing happend lol..so he said he is going to buy a new mainboard...so Im frustrated lol because if i give the card back n the new one acts up aswell it means to buy a new mainboard..and that said I would need to buy a 64bit board because its pointless buyin a non 64bit board because sooner or later i need it anyways for a better CPU..so that in mind im frustrated already because it takes me like 6months to save up money for a new board and then I would need a new cpu aswell since i just got a 32bit sempron..oh well I will give it a few hours testing running some benchmarks now n this n that n tomorrow I just follow my gut feeling n either return it or not..lets see I keep u guys informed tho!

I had 2 9800pros that died whilst idling over night, I didnt believe it was the cards as I would expect them to have died whilst under load, as stated earlier, welcome to PCs! I would try a board and if it still blacks out "take it back and say you bought it for someone for xmas and they've already got it or something like that" then return your card, if it works keep the board, have you tried a mainboard bios flash?

yep the board is flashed to the latest version.. I returned the card today in the shop..there was a broken corner on of those black things (dont know the english word for it) n I just noticed it today after lookin at it properly in the shop the guy said normally he cant take it back then since it has a piece broken off but he returned it anyways but I noticed now that black thing where a corner was broken off the card I got now that black thing has a few scratches on also u can see the card has been "used" because the golden stripes for the AGP slot show marks..Im thinkin that the shop might bought the cards from the manufactur directly but those cards where "used" cards which have been returned but tested n they worked..thats the only way i can explain it to myself..but either way I just could exchange it so lets see if it works..i was talkin with him about it n he said he cant imagine its the graphic card but n my feelings tell me it really isnt but I just blame it right now since its the only part I upgraded lately so I can atleast make sure that the graphic card is ok if the blackouts still occur then its most likely the motherboard or the PSU (eventho I tried 2 different ones)..rams i tested the other day with memtest86 n they were fine..ok lets what happens if it still has blackouts then it wasnt the card n I can start saving money for a new mainboard n CPU... @ leekirlew u know what ever happend to the computer shop? they seemed to have closed down all their shops in the UK over night? I used to shop there but now I just go to maplin..Im going back to london in january so im going to send my PC over there via mail so by the time I arrive my PC arrives there aswell but thank god I have and old crt in london otherwise I would have to send my crt via mail n that would be too expensive lol..

ok so far no blackouts but Im not sure if thats because of the new graphiccard or just simply because im running my CPU / RAM at stock speed...thinkin about it that running my PC at stock speed might give me more power for my graphiccard and so it doesnt blackout or crash..im gonna let it run now for a couple of days with stock speeds n then i overclock it back to where they were before and if its gonna crash then I either need a new PSU or maybe the motherboard is not "strong" enough for the card + the overclocked CPU / RAM at once..just sucks because now I run at 1500mhz again so I lose alot of performance while gaming..